Numerical Simulations of Circular Particles in Parallel-plate Channel Flow Using Lattice Boltzmann Method (original) (raw)
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Lattice Boltzmann Simulation of Particle Laden Flows in Microfluidic Systems
2003
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Lattice Boltzmann analysis of micro-particles transport in pulsating obstructed channel flow
Dispersion and deposition of microparticles are investigated numerically in a channel in the presence of a square obstacle and inlet flow pulsation. Lattice Boltzmann method (LBM) is used to simulate the flow field and modified Euler method is employed to calculate particles trajectories with the assumption of one-way coupling. The forces of drag, gravity, Saffman lift and Brownian motion are included in the particles equation of motion. The effects of pulsation amplitude (AMP), Strouhal number and particles Stokes number (Stk) are rigorously studied on particles dispersion and deposition efficiency. Flow vortex shedding and particles dispersion patterns together with the averaged fluid–particle relative velocity and deposition efficiency plots are all discussed thoroughly. The results show that increment of pulsation amplitude enforces the vortices to form closer to the obstacle until their shape deteriorates as Strouhal number ratio (SNR) rises. The average recirculation length shrinks to its minimum at each studied Amp when SNR escalates to 2. Various behaviors are categorized for dispersion pattern of particles when Stokes number changes from 0.001 to 4. Deposition efficiency is indirectly related to Amp for Stk ≤ 2 while for higher Stokes numbers (2 < Stk ≤ 4) they show direct relationship. Deposition pattern becomes rather independent of SNR at Amp = 0.1. The grid independency test was performed for the LBM analysis, and simulation code was successfully verified against credible benchmarks.
Journal of Aerosol Science, 2010
Particle dispersion and deposition over a square cylinder in a channel flow has been investigated numerically. Two-dimensional fluid flow computations were performed using lattice Boltzmann method (LBM), while a Lagrangian description was used for simulation of spherical, solid particles immersed in the flow. Computational simulations were performed for Reynolds numbers of 120 and 200, where unsteady vortex shedding forms behind the square cylinder. Good agreement was observed between present fluid flow simulations and earlier numerical works. This instantaneous flow field was used to evaluate particle trajectories. Transport and deposition of 0.01-10 mm particles were studied. The forces considered in the equation of particle motion were drag, the Saffman lift, gravity and Brownian forces. The simulation results show that the Brownian diffusion affects the deposition rate of ultrafine particles on the front and the back sides of the block. Motion of particles behind the obstacle is greatly influenced by the vortex shedding.
Lattice-Boltzmann simulations of particle transport in a turbulent channel flow
International Journal of Heat and Mass Transfer, 2018
The lattice-Boltzmann Method (LBM) is employed to directly simulate the transport of particles approximated as 'point particles' in a turbulent channel flow. Prior experimental studies have shown that particles preferentially move toward the wall or center in a pipe flow depending on their Stokes number (St). The simulations are carried out for a range of St and they reproduce the observed experimental behavior. Since the only effect that can influence the transport in the cross-flow direction is turbulence in the context of the simulation framework adopted here, it is concluded that turbophoresis is responsible for the behavior.
JSME International Journal Series C, 2004
This paper describes the prediction of index of thrombus formation in shear blood flow by computational fluid dynamics (CFD) with Lattice Boltzmann Method (LBM), applying to orifice-pipe blood flow and flow around a cylinder, which is simple model of turbulent shear stress in the high speed rotary blood pumps and complicated geometry of medical fluid machines. The results of the flow field in the orifice-pipe flow using LBM are compared with experimental data and those using finite difference method, and it is found that the reattachment length of the backward facing step flow is predicted as precise as that the experiment and the finite difference method. As for thrombus formation, from the computational data of flow around the cylinder in the channel, the thrombus formation (thickness) is estimated using (1) shear rate and adhesion force (effective distance) to the wall independently, and (2) shear rate function with adhesion force (effective distance), and it is found that the prediction method using shear rate function with adhesion force is more accurate than the method using the former one.
A DLM/FD/IB method for simulating cell/cell and cell/particle interaction in microchannels
Chinese Annals of Mathematics, Series B, 2010
A spring model is used to simulate the skeleton structure of the red blood cell (RBC) membrane and to study the red blood cell (RBC) rheology in Poiseuille flow with an immersed boundary method. The lateral migration properties of many cells in Poiseuille flow have been investigated. The authors also combine the above methodology with a distributed Lagrange multiplier/fictitious domain method to simulate the interaction of cells and neutrally buoyant particles in a microchannel for studying the margination of particles.
Numerical simulation of blood with fluid-structure interactions using the lattice-Boltzmann method
2010
The fluid dynamics video presented here outlines recent advances in the simulation of multiphase cellular blood flow through the direct numerical simulations of deformable red blood cells (RBCs) demonstrated through several numerical experiments. Videos show RBC deformations in variety of numerical simulations, relative viscosity of a suspension of RBCs in shear, and the cell-depleted wall layer for blood Hagen-Poiseuille flow.
Computational model of whole blood exhibiting lateral platelet motion induced by red blood cells
International Journal for Numerical Methods in Biomedical Engineering, 2010
An Immersed Boundary method is developed in which the fluid's motion is calculated using the lattice Boltzmann method. The method is applied to explore the experimentally-observed lateral redistribution of platelets and platelet-sized particles in concentrated suspensions of red blood cells undergoing channel flow. Simulations capture red-blood-cell-induced lateral platelet motion and the consequent development of a platelet concentration profile that includes an enhanced concentration within a few microns of the channel walls. In the simulations, the near-wall enhanced concentration develops within approximately 400 msec starting from a random distribution of red blood cells and a uniform distribution of platelet-sized particles.
Journal of Serbian Society for Computational Mechanics
Transport of small particles, of micrometer and sub-micrometer size, by fluid occurs in many technological and biological systems. The channels through which the fluid flows are often with cross-sectional dimensions on the order of several to tens of micrometers. The aim of this study was to investigate effects of shape of micro-and nano-particles on particle trajectories when particles are transported within small channels as blood vessels. Efficiency of therapeutics by particles as the drug carriers is significantly dependent on particle trajectories. It is desirable to have particle trajectories approaching the vessel walls in order to increase therapeutic efficacy. We studied motion of particles in channels (pipes) for two physical conditions: Poiseuille flow, which is characteristic in pipe flow, and shear flow. Shear flow conditions are analyzed since the character of fluid flow near the wall in these systems can be approximated as shear, with a linear change of velocity with the distance from the wall. We here investigated trajectories of particles of different shapes in 2D flow using the finite element (FE) method, with a strong coupling approach for solid-fluid interaction and a remeshing procedure. The results give insight into the characteristics of the particle motion, e.g. trajectories and rotations, under various flow conditions in micron size channels, including flow in the presence of moving deformable discs. We demonstrate that the particle trajectories are essentially parallel to the wall for various conditions and that particle size and shape do not considerably alter the parallel nature of the trajectories.
A comparison of non-Newtonian models for lattice Boltzmann blood flow simulations
Computers & Mathematics with Applications, 2009
In the present paper, three non-Newtonian models for blood are used in a lattice Boltzmann flow solver to simulate non-Newtonian blood flows. Exact analytical solutions for two of these models have been derived and presented for a fully developed 2D channel flow. Original results for the use of the K-L model in addition to the Casson and Carreau-Yasuda models are reported for non-Newtonian flow simulations using a lattice Boltzmann (LB) flow solver. Numerical simulations of non-Newtonian flow in a 2D channel show that these models predict different mass flux and velocity profiles even for the same channel geometry and flow boundary conditions. Which in turn, suggests a more careful model selection for more realistic blood flow simulations. The agreement between predicted velocity profiles and those of exact solutions is excellent, indicating the capability of the LB flow solver for such complex fluid flows.